Water Sucrose Solutions Research Articles

Smartphone-Based Critical Angle Refractometer for Real-Time Monitoring of Brix Value

We demonstrate the first smartphone-based critical angle refractometer for monitoring refractive index and Brix value in real time. The principle design of an optical coupler is based on the total internal reflection of incident light from the phone screen. The images acquired from the front-facing camera are directly analyzed on the smartphone using a custom developed application, to detect the shift of gradient peak position corresponding to the refractive index and Brix value. Calibrations are carried out using nine water-sucrose solutions providing a linear response in the refractive index range of 1.3330–1.3575 RIU (R2 = 0.9984) with the sensitivity and the resolution of 2778.1 pixel/RIU, and $\text {3.6}\times \text {10}^{-\text {4}}$ RIU, and a linear response in the Brix value of 0–16.25 °Brix (R2 = 0.9968) with the sensitivity and the resolution of 4.239 pixel/°Brix and 0.24 °Brix. We also successfully determined the sugar content in six fruit juices with the absolute error from standard refractometer at less than 0.21 °Brix.

Dynamic and sub-ambient thermal transition relationships in water–sucrose solutions

This work was undertaken to investigate thermal and dynamic transitions observed in the temperature range close to the bulk ice melting temperature in sucrose solutions. Measurements of thermal (differential calorimetry) and dynamic (neutron scattering) properties were compared in order to give a physical interpretation of the thermal transitions observed during the thawing of amorphous sucrose solutions. In fact, the freezing of biological material leads to the distinction between different pools of water: bulk water which becomes ice after freezing, unfrozen water trapped in the glassy matrix or close to the interface of solutes can be considered, and finally freezable confined water with a lower melting point than bulk water and with properties depending on both the ice presence and the microstructure of the material. The transition temperatures such as glass transition or melting are dependent on the freezing protocol used and examples of annealing effects are presented, in order to underline the necessity of a good temperature control during freezing for the study of biological material with freezable water.

EFFECTIVE DIFFUSION COEFFICIENTS BEHAVIOR IN OSMOTIC DEHYDRATION OF APPLE SLICES CONSIDERING SHRINKING AND LOCAL CONCENTRATION DEPENDENCE

ABSTRACT The mass transfer during osmotic dehydration of apple slices immersed in 40, 50 and 60% (w/w) aqueous sucrose solutions was investigated to evaluate the influence of solution concentration on diffusivities. In the mathematical model, the diffusion coefficients were functions of the local water and sucrose concentration. The mass transfer equations were, simultaneously, solved for water and sucrose using an implicit numerical method. Material coordinates following the shrinkage of the solid were used. The predicted concentration profiles were integrated and compared to experimental data, showing a reasonable agreement with the measured data. On average, the effective diffusion coefficients for water and sucrose decreased as the osmotic solution concentration increased; that is the behavior of the binary coefficients in water–sucrose solutions. However, the diffusivities expressed as a function of the local concentration in the slices varied between the treatments. Water diffusion coefficients showed a remarkable variation throughout the slice and unusual behavior, which was associated to the cellular structure changes observed in tissue immersed in osmotic solutions. Cell structure changes occurred in different ways: moderate plasmolysis at 40%, accentuated plasmolysis at 50% and generalized damage of the cells at 60%. Intact vacuoles were observed after a long time of exposure (30 h) to 40 and 50% solutions. Effects of the concentration on tissue changes make it difficult to generalize the behavior of diffusion coefficients. PRACTICAL APPLICATIONSThe main innovation introduced in this study is represented by the model formulation that allows simulation of the concentration profiles during osmotic dehydration with a reasonable degree of accuracy. The model is useful for the design and control of this process and of further operations such as convective drying, as nonhomogeneous initial conditions can be established. In addition, the diffusivities expressed as a function of the local concentration in the slices allows interpretation of some of the physical changes in plant tissues exposed to concentrated solutions.

Mass transfer phenomena during the osmotic dehydration of apple isolated protoplasts ( Malus domestica var. Fuji)

Osmotic dehydration (OD) experiments of apple isolated protoplasts at different temperatures (30, 40 and 50 °C) and different water–sucrose solutions (25%, 35% and 45% w/w) were monitored. The experiments were carried out under a light microscope (mod. DM LM, Leica Microsystems) with a heating/freezing stage and standalone temperature programmer (mod. LTS350 and mod. TMS94, Linkam Scientific Ltd.), where protoplasts were maintained at controlled temperature during dehydration experiences. Sequence images were acquired at different times with a CCD camera in order to measure volume changes and to determine trans-membrane water flux. The projected area ( A) of individual protoplasts was measured with Adobe Photoshop (Adobe, v.7.0). Mass transfer kinetics was analyzed, determining the phenomenological coefficient ( L w) and the permeability ( D ew/ d PM) of the plasmalemma. Results were in the range of those obtained by other authors: L w = [(30 °C) 4.5 ± 0.3; (40 °C) 6.5 ± 0.4; (50 °C) 9.9 ± 0.6] × 10 −5 (mol 2 J −1 m −2 s −1); D ew/ d PM = [(30 °C) 3.3 ± 0.3; (40 °C) 5.0 ± 0.4; (50 °C) 7.9 ± 0.4] × 10 −3 (m s −1). Temperature dependence was evaluated by fitting the results to an Arrhenius plot, and activation energy was calculated for both cases ( E a = [32.4–38.8] kJ/mol).

Effect of operating conditions on water transport during the concentration of sucrose solutions by osmotic distillation

A recent membrane technique, osmotic distillation (OD), is used to concentrate binary water–sucrose solutions at ambient temperature under atmospheric pressure. The principle is based on the extraction of water vapour from a dilute aqueous solution, which is put in contact with a hypertonic salt solution by means of a macroporous hydrophobic membrane. The concentration difference between both solutions translates into a transmembrane vapour pressure drop, that constitutes the driving force for mass transfer. An experimental device is designed at laboratory scale for this study, allowing achievement of vapour fluxes of 10 kg m −2 h −1 under standard conditions. The effect of various operating parameters on vapour flux is studied. The solute content results in the most influencing variable via water activity in brine and via viscosity in sugar solutions. The effect of concentration polarisation on the brine side is not negligible and would have to be taken into account for process optimisation. This phenomenon could not be quantified on the sugar solution side due to pressure drop limits of the pilot rig. Eventually, the vapour flux can be significantly increased by adding a temperature difference to the transmembrane concentration difference, when pure water is evaporated.

The Effects of Calcium Chloride and Sucrose Prefreezing Treatments on the Structure of Strawberry Tissues

The structural changes in strawberry tissues during prefreezing treatments, freezing and thawing were studied by means of textural and drip loss measurements as well as by bright-field and confocal laser scanning microscopy (CLSM), and by Fourier transform infrared (FT-IR) microscopy. Calcium chloride or sucrose were used as dipping pretreatment agents before freezing. In the calcium chloride test series a full factorial screening design was used. The three-level factors included were the CaCl2concentration of the dipping solution, the dipping time and the temperature of the solution. Two kinds of sucrose treatments were used. Strawberries were either dipped in water–sucrose solutions or were sprinkled with crystallized sucrose. The CaCl2or sucrose pretreatments did not significantly affect the drip loss of thawed strawberries compared to water dips or untreated reference samples. The pretreated strawberries were firmer than the untreated control samples but some of the CaCl2- and sucrose-treated strawberries were less firm than the strawberries dipped in water. According to microscopical studies, both CaCl2and crystallized sucrose pretreatments affected the microstructure of strawberry tissues. These pretreatments especially affected pectin, protein, lignin and structural carbohydrates in the vascular tissue and cortex compared to the untreated reference samples. CaCl2-treatment had an even stronger effect than sucrose on the above compounds except lignin. The pretreatments did not seem to affect the epidermis, hypodermis or pith.

Kinetic-Turbidimetric Determination of Stachyose Based on Its Inhibitory Action on Sucrose Crystallization.

Abstract The effects of 9 saccharides on the crystallization of sucrose have been comparatively studied with analytical purposes. A sensitive (detection limit 0.1 μg mL−1) and simple kinetic turbidimetric procedure is used for determination of stachyose, based on its inhibitory action on the crystallization of sucrose. The supersaturated solutions of sucrose were prepared by addition of acetone to stable water sucrose solutions. The induction period of the crystallization process was turbidimetrically measured. Controlled constant stirring and temperature are convenient in order to obtain reproducible results. The method was applied to the determination of stachyose in synthetic mixtures.

Y (Grunwald-Winstein) parameters of aqueous solutions of sugars

The kinetics of solvolysis of t-butyl chloride in water-glucose and water-sucrose solutions have been studied. From the data obtained, Y Grunwald-Winstein parameters corresponding to these mixtures have been derived.

Atomic test of the Stokes-Einstein law: Diffusion and solubility of Xe

The diffusion coefficient $D$ and the Ostwald solubility $\ensuremath{\alpha}$ have been measured for $^{133}\mathrm{Xe}$ atoms in water-sucrose solutions ranging in viscosity $\ensuremath{\eta}$ from 1 to 289 cP, i.e., 0.68% sucrose by weight. In water $D(20\ifmmode^\circ\else\textdegree\fi{}\mathrm{C})=(1.32\ifmmode\pm\else\textpm\fi{}0.05)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5}$ ${\mathrm{cm}}^{2}$/sec, in agreement with the Stokes-Einstein (SE) law. Over the entire range studied the observed dependence is $D\ensuremath{\propto}{\ensuremath{\eta}}^{\ensuremath{-}0.63\ifmmode\pm\else\textpm\fi{}0.02}$, significantly departing from the SE law. In water $\ensuremath{\alpha}(20\ifmmode^\circ\else\textdegree\fi{}\mathrm{C})=0.108\ifmmode\pm\else\textpm\fi{}0.005$. For water-sucrose solutions $\ensuremath{\alpha}$ is approximately proportional to the volume fraction of water in solution.

Tarsal Taste Discrimination in the Blowfly, Calliphora Vicina Robineau-Desvoidy

This paper deals with the problem of the specificity of the sense cells in terminal tarsal taste sensilla on the forelegs of the blowfly, Calliphora vicina Rob.-Desv. (= Calliphora erythrocephala Meigen), in relation to the discrimination these flies are capable of making, as judged by their behavioural responses, between water and weak sugar (sucrose) solutions. First, electrophysiologically recorded responses to pure water are described. As many as three receptor cells in the blowfly terminal tarsal taste hairs can be stimulated by water. Next, the reactions of sense cells to both water and weak sucrose solutions are analysed, showing that up to concentrations of several hundredths of Molar sucrose the responses are indistinguishable from those to water. It is therefore surmised that water and sucrose stimulate the same sense cells in these taste hairs, which raises doubts concerning the specificity generally ascribed to these cells. These doubts are confirmed by the results of experiments showing that water and sucrose adapt, and therefore stimulate, the same sense cells. This finding implies that some mechanism other than specificity of sugar- and water-sensitive cells is required to explain the behavioural distinction shown by blowflies between water and sucrose. Before an alternative was formulated, the comparability of the proboscis response in fixed and in free-moving flies was discussed, and also to what extent single-hair stimulations (such as are usually applied in electrophysiological methods) are comparable with multiple-hair stimulations (as usually applied in behavioural experiments). Both questions could be answered satisfactorily and consequently an alternative for cellular specificity is given. It involves the concept that discrimination occurs in the intact animal on the basis of the input from many tarsal hairs, the cells of each of which respond with different relative impulse frequencies to stimulation with water and to stimulation with weak sucrose solutions.

Effect of sucrose on hydroerosion of steels

The erosion of carbon and stainless steels under the influence of the impact of a jet of water and aqueous sucrose solutions was studied. It was established that increasing the sucrose concentration (i.e., density) of a solution intensifies the brittle fracture of steels.

Interfacial Effects in Immiscible Liquid-Liquid Displacement in Porous Media

Abstract A study was made of the effects of wettability and interfacial tension the immiscible displacement of a liquid by another liquid for porous media. The influence of viscosity ratio was also investigated. Porous media used were polytetrafluoroethylene (TFE) cores prepared by compressing TFE powder under different pressures. It is shown that displacement of a wetting by a nonwetting liquid is always less efficient than the displacement of a nonwetting by a wetting fluid, all other things being equal. In the former case, the recovery efficiency can be increased substantially by either reducing the interfacial tension or increasing the viscosity of the displacing fluid. A qualitative discussion is given on the implications of this work to the recovery of crude oil by waterflooding. Introduction The high cost of oil exploration and new recovery schemes makes it imperative that waterflooding be conducted under conditions favoring most efficient oil recovery. To improve oil recovery by waterflooding, it is essential that the role played by interfacial forces in the entrapment of residual oil be studied and understood. Interfacial phenomena in natural rock, connate water and crude oil systems are very complicated because of the complexity of the natural liquids found in petroleum reservoirs, because of our inability to adequately describe the geometrical structure of the porous media and because of a lack of understanding of physical and chemical interactions between the liquids and surface of the pores. The problem becomes further complicated when one tries to elucidate the role of interfacial phenomena in fluid flow. Numerous studies of the displacement of oil by water under different interfacial tension or wettability conditions have been made. These studies have been performed in silica, alundum or sandstone systems using water and paraffin oil and also some surface active material to control the interfacial tension or and the contact angle. Unfortunately, the high energies of various interfaces involved favor adsorption and orientation of the surface active material at the intrafaces. Also the surface active material concentration at the interfaces exceeds that in the bulk of the liquid phases. Such surface excess may cause the surfactant distribution, the contact angle and the interfacial tension to differ from their measured static equilibrium values and makes interpretation of the displacement experiments difficult. Furthermore, as changes in also lead to changes in cos, the role played individually by one of these parameters in the displacement becomes obscured by the effect of the other. To circumvent these difficulties, a low surface energy solid and true solutions or pure liquids should be used. Use of a low surface energy solid minimizes adsorption and orientation effects at the solid-liquid interfaces. By controlling and cos through use of selected pairs of pure liquids or true solutions rather than by surfactants, the adsorption effects at liquid-liquid interfaces are eliminated. In the present study TFE cores were used as me porous media. Liquids used were water sucrose solutions, paraffin oils and benzyl, n-butyl and isobutyl alcohols. The interfacial tension was varied from 40 to 1.1 dynes/cm by suitably choosing the liquid pair. A surface above material was added to the water-oil system only in the case where interfacial tension of 0.5 dynes/ cm was desired. No precise changes of cos were attempted. However, either the displaced or the displacing liquid could be made the one which preferentially wets the TFE surface. Using sucrose solutions and blends of paraffin oils proved to be a convenient way of changing the viscosity ratio between the displaced and displacing liquids. The present investigation examines the effect of interfacial tension, wettability and viscosity ratio on the immiscible liquid-liquid displacement from porous media. SPEJ P. 217ˆ

Nectar Secretion in Excised Flowers. III. the Dual Effect of Indolyl-3-Acetic Acid

SUMMARYThe quantity of nectar sugar secreted by excised Antirrhinum flowers was reduced when indolyl-3-acetic acid (IAA) was added to the culture solution at 5 × 10−4M concentration. The volume of fluid was reduced by IAA in culture solutions containing 5–20% sucrose, but increased by IAA in pure water or dilute sucrose solutions. Pre-treatment with IAA produced the same effects as constant exposure. Calcium and potassium ions modified the action of IAA on water excretion. Nectaries of IAA-treated flowers differed in microscopic appearance from those of controls, and resembled the nectaries of flowers cultured in pure water. A dual effect of IAA on sugar and water excretion is inferred and, as a corollary, a partial independence of movement of the solid and liquid components of nectar. The evidence is not conclusive as to whether IAA affects the secretory mechanism directly, or the transport of sugar to the nectary.